Inadvertent ketamine overdose in children: clinical manifestations and outcome

Knowledge of procedural sedation and analgesia of emergency medicine physicians

OBJECTIVES

Pediatric procedural sedation and analgesia (PSA) is unique. The goals of this study were to examine emergency medicine (EM) physicians' baseline knowledge of general and pediatric PSA compared with that of other nonanesthesiologist physicians and to test effectiveness of a seminar required for credentialing in PSA.

METHODS

This was a retrospective, before and after interventional study of participants in a major university teaching hospital's PSA course. Analysis was conducted to determine: (1) performance of EM physicians on questions related to general and pediatric PSA compared with other participating physicians, and (2) effect of seminar on participants' knowledge of PSA.

RESULTS

The mean +/- SE PSA pretest score for EM physicians was higher than that of other physicians (63.7% +/- 1.1% vs 50.2% +/- 2.2%, P < 0.001), but not for the pediatric PSA pretest scores (54.8% +/- 1.7% vs 51.0% +/- 1.8%, P = 0.17). The EM practitioners performed worse on the pediatric versus the adult portion of the PSA pretest (55.2% +/- 1.8% vs 66.8% +/- 1.4%, P < 0.001). Practitioners trained in American Heart Association advanced life support classes performed better than the untrained (52.1 +/- 1.4 vs 41.6+/- 2.5, P < 0.001). Total and pediatric PSA test scores improved significantly after educational intervention in all practitioners.

CONCLUSIONS

The EM physicians have stronger knowledge about general PSA than other nonanesthesiologist physician participants, but not for pediatric PSA, thus providing a target for future interventions. This course on PSA improved practitioners' knowledge of general and pediatric PSA and can be used as an educational model for PSA training. Further study is needed to determine decay rates for this knowledge and impact on patient care.

Prospective randomized trial evaluating ketamine for advanced endoscopic procedures in difficult to sedate patients

BACKGROUND

Adequate patient sedation is mandatory for advanced endoscopic procedures such as ERCP and EUS.

AIM

To evaluate the effectiveness and safety of ketamine in difficult to sedate patients undergoing advanced endoscopic procedures.

METHODS

This was a prospective, randomized trial of all patients undergoing ERCP or EUS who were not adequately sedated despite administration of meperidine 50 mg, midazolam 5 mg and diazepam 5 mg. Patients during endoscopy were then randomized to receive either intravenous ketamine (20 mg) every 5 min or continue to receive standard sedation using meperidine and diazepam.

RESULTS

Of 175 patients, 82 were randomized to receive ketamine and 93 standard sedatives. Compared with standard sedation, qualitative physician rating (P < 0.0001) and depth of sedation (P < 0.001) were superior in the ketamine group with shorter recovery times (P < 0.0001). Both patient discomfort and sedation-related technical difficulty were significantly less among patients randomized to receive ketamine (P < 0.0001). More patients in the standard sedation group were crossed-over to the ketamine group due to sedation failure (35.5 vs. 3.7%, P < 0.0001). Nine patients who received ketamine, developed adverse events that were managed conservatively.

CONCLUSIONS

Ketamine is a useful adjunct to conscious sedation in patients who are difficult to sedate. Its use Results in better quality and depth of sedation with shorter recovery times than patients sedated using benzodiazepines and meperidine alone. Further prospective studies evaluating the effectiveness and safety of ketamine for endoscopic sedation are needed.

Ketamine : from medicine to misuse

This review describes the medical, research and recreational uses of ketamine, an anaesthetic derivative of phencyclidine that has dissociative, analgesic and psychedelic properties. Ketamine has a complex mechanism of action that is further complicated by stereoselectivity; however, antagonism of glutamate NDMA receptors is thought to underlie its analgesic, dissociative and neuroprotective effects. While ketamine use in medical and veterinary settings is well documented and has a good safety record, the increase in its unregulated use outside of such controlled environments is a cause for concern. The impact on higher centres in the brain, particularly altered perception of auditory, visual and painful stimuli, results in a general lack of responsive awareness that puts the recreational user at (often unrecognised) risk of personal harm. The perceptual and mood changes observed in those who have consumed ketamine are highly sensitive to age, dose, route of administration, previous experience and setting. At low doses, stimulant effects predominate and the effect of environmental conditions are significant; with higher doses, psychedelic effects predominate and the effect of the environment diminishes. The potential of ketamine as a novel clinical and research tool is matched by its abuse potential outside medical settings.

Pain management in the wilderness and operational setting

The wilderness and operational setting places unique constraints on one's ability to treat pain. In this article we will discuss methods for treating pain both in the wilderness and operational setting. By operational we mean the austere deployed military setting, to include both noncombat and combat operations. The authors combined experience with wartime trauma pain management consists of experience in Operation "Just Cause" (Panama Invasion), Operation "Desert Storm" (Persian Gulf War), Operation "Uphold Democracy" (Haiti liberation), Operation "Enduring Freedom" (Afghanistan conflict), and Operation "Iraqi Freedom" (Iraq conflict).

Procedural Sedation and Analgesia in the Emergency Department: What Are the Risks?

The practitioner of emergency medicine is routinely faced with patients in need of emergent procedures and pain control and sedation. Our challenge is to make our patients' experiences as painless and as safe as possible, while maximizing our ability to perform the procedure at hand; this is not always an easy task given the propensity of each human body to react differently to interventions and stimuli. We can best meet this challenge by understanding how our patients and pharmaceutical agents intermingle in the risk-benefit equation we formulate before starting our "experiment." Coupling this information with fundamentally sound patient care and monitoring will minimize bad experiences with PSA for both the patient and practitioner.

Ketamine for paediatric sedation/analgesia in the emergency department

This review investigates the use of ketamine for paediatric sedation and analgesia in the emergency department.

Acute toxic effects of club drugs

This article summarizes the short-term physiological toxicity and the adverse behavioral effects of four substances (GHB, ketamine, MDMA, and Rohypnol) that have been used at latenight dance clubs. The two primary data sources were case studies of human fatalities and experimental studies with laboratory animals. A safety ratio was calculated for each substance based on its estimated lethal dose and its customary recreational dose. GHB (gamma-hydroxybutyrate) appears to be the most physiologically toxic; Rohypnol (flunitrazepam) appears to be the least physiologically toxic. The single most risk-producing behavior of club drug users is combining psychoactive substances, usually involving alcohol. Hazardous drug-use sequelae such as accidents, aggressive behavior, and addiction were not factored into the safety ratio estimates.

Comparison of acute lethal toxicity of commonly abused psychoactive substances

AIMS

To determine the acute lethal toxicity of a range of psychoactive substances in terms of the dose customarily used as a single substance for non-medical purposes.

DESIGN AND METHOD

A structured English-language literature search was conducted to identify experimental studies and clinical reports that documented human and non-human lethal doses of 20 abused substances that are distributed widely in Europe and North America. Four inclusion criteria were specified for the reports, and approximately 3000 relevant records were retrieved from search engines at Biosis, Science Citation Index, Google and the National Library of Medicine's Gateway. In order to account for different drug potencies, a 'safety ratio' was computed for each substance by comparing its reported acute lethal dose with the dose most commonly used for non-medical purposes.

FINDINGS

The majority of published reports of acute lethal toxicity indicate that the decedent used a co-intoxicant (most often alcohol). The calculated safety ratios varied between substances by more than a factor of 100. Intravenous heroin appeared to have the greatest direct physiological toxicity; several hallucinogens appeared to have the least direct physiological toxicity.

CONCLUSIONS

Despite residual uncertainties, the substantial difference in safety ratios suggests that abused substances can be rank-ordered on the basis of their potential acute lethality.

Safety and effectiveness of ketamine as a sedative agent for pediatric GI endoscopy

BACKGROUND

The ideal sedation for children undergoing GI endoscopy remains elusive. After ketamine was introduced as a sedative agent in our GI procedure suite, improved sedation and reduced complications were observed. The aim of this study was to assess the safety and effectiveness of ketamine as a sedative agent for GI endoscopy in pediatric patients.

METHODS

A retrospective cohort study of 402 procedures (EGD, colonoscopy) was performed. Sedation-related complications were defined as hypoxia (oxygen saturation <95% by pulse oximetry), agitation, emergence reactions, stridor, laryngospasm, nausea, vomiting, aspiration, and muscle twitching, or any combination thereof. Sedation groups were defined as the following: Group I, midazolam and meperidine (n=192); Group II, midazolam, meperidine, and ketamine (n=82); and Group III, midazolam and ketamine (n=128).

RESULTS

Group 1 (midazolam and meperidine) had the highest frequency of complications, most commonly hypoxia. Group 3 (midazolam and ketamine) had the lowest rate of complications (p=0.001) and the highest rate of adequate sedation, although the difference was not significant (p=0.07).

CONCLUSIONS

The combination of midazolam and ketamine appears to provide safe and effective sedation for pediatric patients undergoing endoscopy.

Prolonged pre-procedure fasting time is unnecessary when using titrated intravenous ketamine for paediatric procedural sedation

BACKGROUND

Paediatric procedural sedation (PPS) is a common procedure in most general EDs. Many departmental guidelines suggest mandatory fasting times for children undergoing PPS, in an attempt to decrease the incidence of postoperative vomiting and (theoretically) aspiration pneumonitis, despite there being little or no evidence in the literature to support these mandatory fasting times.

OBJECTIVES

To prospectively address the relationship between preprocedure fasting time and intraprocedure or postprocedure vomiting in children aged 1-12 years undergoing procedural sedation with intravenous ketamine in the ED.

METHODS

From January 1999 to May 2000 all children presenting to the Royal Darwin Hospital Emergency Department with a condition requiring ketamine PPS were enrolled for data collection after parental consent was obtained. Titrated intravenous ketamine was administered via protocol. Prospective ED procedural sedation data collection forms of 272 consecutive cases of titrated intravenous ketamine sedation were reviewed.

RESULTS

Fasting time was accurately recorded on 257 (95%) data collection forms. There was no intraprocedure vomiting. Overall rate of postprocedure vomiting was 13.9%. No statistically significant association between decreased fasting time and increased incidence of vomiting was found. In fact, there was a trend towards increased incidence of vomiting with increased fasting time (P = 0.08). The rate of vomiting of those children fasted 3 h or greater preprocedure (20/127 or 15.8%) was over twice the rate of those fasted less than 1 hour (2/30 or 6.6%). Incidence of vomiting was significantly associated with increasing age (P = 0.0007). No clinically evident aspiration pneumonitis occurred.

CONCLUSION

Prolonged preprocedure fasting time did not reduce the incidence of postprocedure vomiting in this case series; to the contrary there was a increased incidence of vomiting with longer fasting times (P = 0.08). There was an increase in postprocedure vomiting with increasing age of the patients.

Anaesthetic consequences for a child with complex multilevel airway obstruction -- recommendations for avoiding life-threatening sequelae

A boy with a suspected lymphoid malignancy presented with gross head and neck lymphadenopathy, a middle mediastinal mass, and rapidly worsening airway obstruction. General anaesthesia was required for definitive histopathological diagnosis. The combination of nasopharyngeal obstruction, malignant infiltration of the tonsils and pharynx, laryngeal displacement, and potential tracheal compression put this patient at extreme risk for perioperative airway complications. Risk assessment, and the impact of anaesthesia on pharyngeal neuromechanical function and mediastinal masses are discussed. Caution with volatile anaesthetic agents is recommended in the patient with an inherently unstable pharynx and/or trachea, in whom airway patency relies on a spontaneously breathing technique and intact airway reflexes.

Procedural sedation for children with special health care needs

Children with special health care needs represent a growing percentage of pediatric patients treated in all emergency departments. Substantial literature exists concerning the medical treatment of these patients, but there is little written describing the management of procedural sedation or analgesia in this population. This article examines the unique anatomic and physiologic implications of procedural sedation or analgesia management in children with special health care needs.

Comparison of propofol/fentanyl versus ketamine/midazolam for brief orthopedic procedural sedation in a pediatric emergency department

PURPOSE

To compare the effectiveness of 2 medication regimens, propofol/fentanyl (P/F) and ketamine/midazolam (K/M), for brief orthopedic emergency department procedural sedation. This study was powered to compare recovery times (RT) and procedural distress as measured by the Observational Score of Behavioral Distress-revised (OSBD-r; range: 0-23.5 with 23.5 representing maximal distress).

METHODS

We conducted a prospective, partially-blinded controlled comparative trial comparing intravenous P/F with K/M in a convenience sample of 113 patients aged 3 to 18 years old undergoing orthopedic procedural sedation. All medications were administered by the intermittent intravenous bolus method. An independent sedation nurse recorded total sedation time and RT. Effectiveness was measured using 6 parameters: 1) patient distress as assessed by independent blinded observers after videotape review using the OSBD-r; 2) orthopedic satisfaction score (Likert scale 1-5); 3) sedation nurse satisfaction score (Likert 1-5); 4) parental perception of procedural pain using a 0 to 100 mm Visual Analog Scale with the upper limit being "most pain"; 5) patient recall of the procedure; and 6) 1 to 3 week follow-up.

RESULTS

RT and total sedation time were significantly less in the P/F group than in the K/M group (33.4 minutes vs 23.2 minutes). The mean OSBD-r scores during manipulation were 0.084 and 0.278 for the K/M and P/F groups, respectively. Although this difference was statistically significant (95% confidence interval for the mean difference -0.34 to -0.048), both regimens were successful in keeping the scores low. There was no statistical difference between the groups in the other measures of effectiveness. There was a statistically significant difference between the groups in the occurrence of desaturation and late side effects.

CONCLUSIONS

RT with P/F is shorter than with K/M. P/F is comparable to K/M in reducing procedural distress associated with painful orthopedic procedures in the pediatric emergency department. Although propofol has a greater potential of respiratory depression and airway obstruction as compared with ketamine, it offers some unique advantages including a quicker offset and smoother recovery profile.

Ketamine: its use in the emergency department

Ketamine has been known to the medical world for over 30 years, yet is not widely used to its full potential. It is often considered to be a 'third world' drug only. In light of a recent increase in interest in its use in the developed world, this review is for emergency physicians to use as a quick reference.

Paediatric cataract blindness in the developing world: surgical techniques and intraocular lenses in the new millennium

Paediatric cataract blindness presents an enormous problem to developing countries in terms of human morbidity, economic loss, and social burden. Managing cataracts in children remains a challenge: treatment is often difficult, tedious, and requires a dedicated team effort. To assure the best long term outcome for cataract blind children, appropriate paediatric surgical techniques need to be defined and adopted by ophthalmic surgeons of developing countries. The high cost of operative equipment and the uneven world distribution of ophthalmologists, paediatricians, and anaesthetists create unique challenges. This review focuses on issues related to paediatric cataract management that are appropriate and suitable for ophthalmic surgeons in the developing world. Practical guidelines and recommendations have also been provided for ophthalmic surgeons and health planners dealing with childhood cataract management in the developing world.

Contemporary trends in pediatric sedation and analgesia

The ability to provide safe, effective procedural sedation and analgesia is a necessary skill for physicians caring for the acutely ill or injured pediatric patient. They physician should be familiar with the agent(s) chosen, including dosage, duration, adverse effects, and contraindications. The choice of agent and regimen should be individualized for the patient and situation. Successful outcomes depend on performing careful pre- and post-sedation evaluations, following appropriate monitoring and equipment guidelines, and having the knowledge and skills to manage any adverse cardiorespiratory event.